Non-volatile memory with adaptive dummy word line bias
A non-volatile storage apparatus includes non-volatile memory cells, word lines connected to the non-volatile memory cells, and a control circuit connected to the word lines and the memory cells. The word lines include data word lines and dummy word lines. Memory cells connected to data word lines are configured to store host data. Memory cells connected to dummy word lines do not store host data. The control circuit is configured to erase, program and read the memory cells. Errors from threshold voltage up-shifting in the memory cells connected to dummy word lines is prevented by adjusting the voltage applied to dummy word lines.
1 . A method, comprising:
trimming a property of a programming voltage signal for a non-volatile memory, the property of the programming voltage signal is a maximum voltage of a programming signal applied to selected word lines; and
trimming a voltage to be applied to dummy word lines of the non-volatile memory based on the trimming of the property of the programming voltage signal.
2 . The method of claim 1 , further comprising:
programming the non-volatile memory with the trimmed property and the trimmed voltage including applying multiple program voltage pulses to the non-volatile memory such that the program voltage pulses increase in voltage magnitude from pulse-to-pulse, the voltage to be applied to dummy word lines is applied while applying the program voltage pulses and increases in voltage magnitude from pulse-to-pulse.
3 . The method of claim 1 , wherein:
the trimming the property includes increasing the maximum voltage of the programming signal applied to the selected word lines; and
the trimming the voltage to be applied to dummy word lines includes increasing the voltage to be applied to dummy word lines by a same amount as the increasing of the maximum voltage of the programming signal applied to selected word lines.
4 . The method of claim 1 , further comprising:
fabricating the non-volatile memory; and
performing die sort for the non-volatile memory, the trimming the property of the programming voltage signal and the trimming the voltage to be applied to dummy word lines are performed during die sort.
5 . The method of claim 1 , further comprising:
programming the non-volatile memory with the trimmed property and trimmed voltage, including further adjusting the voltage to be applied to dummy word lines based on a number of erase/program cycles performed.
6 . A non-volatile storage apparatus, comprising:
a memory structure comprising non-volatile memory cells and word lines connected to the memory cells, the word lines include data word lines and dummy word lines; and
a control circuit connected to the word lines and the memory cells, the control circuit is configured to program the memory cells by:
applying multiple program voltage pulses to the memory cells such that the program voltage pulses increase in voltage magnitude from pulse-to-pulse;
applying a voltage to the dummy word lines while applying the program voltage pulses; and
increasing voltage magnitude of the voltage applied to the dummy word lines from pulse-to-pulse such that an initial value of the voltage applied to the dummy word lines is set based on a maximum voltage of the multiple program voltage pulses.
7 . The non-volatile storage apparatus of claim 6 , wherein:
the control circuit is configured to perform memory operations on the memory cells, the control circuit is configured to increase a voltage applied to dummy word lines during one or more memory operations based on a number of erase/program cycles performed.
8 . The non-volatile storage apparatus of claim 7 , wherein:
the non-volatile memory cells are arranged in a block; and
the control circuit is configured to increase the voltage applied to dummy word lines during one or more memory operations based on the number of erase/program cycles performed on the block.
9 . The non-volatile storage apparatus of claim 7 , wherein:
the control circuit is configured to increase the voltage applied to dummy word lines during programming operations based on the number of erase/program cycles performed.
10 . The non-volatile storage apparatus of claim 7 , wherein:
the control circuit is configured to increase the voltage applied to dummy word lines during sensing operations based on the number of erase/program cycles performed.
11 . The non-volatile storage apparatus of claim 7 , wherein:
the control circuit is configured to increase the voltage applied to dummy word lines during programming operations based on the number of erase/program cycles performed and increase the voltage applied to dummy word lines during sensing operations based on the number of erase/program cycles performed.
12 . The non-volatile storage apparatus of claim 7 , wherein:
the memory structure comprises a first stack of word line layers alternating with dielectric layers, a second stack of word line layers alternating with dielectric layers, and a Joint area between the first stack and the second stack; and
the dummy word lines are adjacent to the Joint area.